The present disclosure herein relates to a transparent display apparatus, and more particularly, to a transparent display apparatus including an organic light emitting diode.
In recent years, a demand for a display device that has excellent emission efficiency, luminance, and viewing angle and fast response speed has been increasing. A liquid crystal display device of flat display devices requires a backlight as a separate light source and has a technical limitation in brightness, contrast rate, and viewing angle.
Accordingly, a display device, which may emit light itself not to require an additional light source and have relatively excellent brightness, contrast range, and viewing angle, has been increasingly interested. Thus, a transparent display device, which allows light to pass through front and rear surfaces thereof not to prevent one's view and simultaneously displays an image, has been actively developing. The transparent display device includes an emission type display device and a reflective display device. The emission type display device is composed of a shutter region and an emitting region. The reflective display device is only composed of a shutter region. For example, the transparent display apparatus is applied to a large TV, advertising screens, home appliances, monitors, small smart devices (e.g. phone and watch), electron guns and electronic shelf labels.
For example, an organic thin film of an organic light emitting diode is transparent in a visible ray region due to difference between absorption spectrum and light emitting spectrum, and an indium tin oxide (ITO) used for an anode electrode is also transparent in the visible ray region. Thus, when a cathode electrode of the organic light emitting diode is made of a transparent material, the transparent organic light emitting display device may be manufactured.
When the organic light emitting diode emits light to display an image, if the light incident into a rear surface is transmitted to a front surface, the contrast rate may decrease to degrade a display quality. Also, since a transparent region does not block the incident light, a black screen may not be displayed.